> If the benefits were great enough (reduced pollution indirectly saving lives? saved life-years due to more efficient traffic?) one could even accept that they could be a little less safe as far as direct fatalities are concerned.

I disagree. I'm finding it hard to come up with an example that would make me think it's ok to have more people hit and killed by cars. I'm more than ready for self-driving cars to be a reality, but not if more people will die. "Saved life-years" is not good enough.